Composite drill.



4.. 0 9 l 5, R. P A D E `T. N E ml. A P 3 0 9 l1 un Nmw WDN 0 D` DE IH s mmm WMM OA U Gm P P A om 3 3, 6 5 7 0|, N

N0 MODEL.

a my *i if www 5mm/11,450@

l No. 756,339.

y ihvirnn @rares Patented April 5, ieee.

lmnfrnnr @tripa WILLIAM R. Dowivwor READING, rEnNsYLvANiA.

2 GOWIPCSITE DRlLL.

SPECIFICATION forming Vpart of Letters Patent No. 756,839, dated pril 5, 1904.

l Application iled November 14:, 1903.' Serial No; 181,250. (No model.) r

To ctZZ` whom zit may concern.:

Be it lrnown that I, WILLIAM R. DOWN, a citizen of the United States, residing in the city of Reading, county of Berks, State of Pennsylvania, have invented certain new and useful lImprovements in Composite Drills, of which the following is a specification.

My invention 'relates particularly to that' class of drills technically known as twistdrills; andmy object is to provide an' improved two-part construction providing for the ready and satisfactory renewalof the cutting end portion .of the drill upon the repeatedlyLused body or shank portion of same.

The high-speed alloy steel now largely employed for twist-drills and other metal-cutting tools because of its being adapted to maintain its hardness notwithstanding the ordinarily ruinous heating incident to present high-speed work is so high-priced as to cause an excessive loss in discarding the main portion of a drill after the cutting end portion thereof has beenreduced by service. Moreover, this high-grade steel While remarkably well adapted for cutting purposes is rather inferior to much lower-priced material so far as the shank requirements are concerned. In view of these facts a twist-drill of composite structure would obviously be advantageous, providing that the different materials comprising it be so united as to both insure satisfactory operation as a complete tool and convenient and accurate renewal of the cutting end portion thereof when required. My invention relates to improved means of effecting this, asparticularly described hereinafter in connection with the accompanying drawings,

and the novel. features of `which are specifically pointed out in the sulpjoin'ed claims.

Figure l is an elevation of a complete two part drill embodying' my complete invention.4

Figs. 2 and Saro separate elevations of the two partsdisunited. Figs. 4 and 'are simllar views ofthe two parts as first formed preliminary to forming the spiral grooves therein. Figs. 6 and 7 are separate plan views ot' the engaging ends of the completed respective portions, and Figs. .8 and 9 are similar views of the ungrooved parts indicated in Figs. 4;

indicates a modification.

tion to be united by a yquarter-turn. Fig. 11 i The'body or shank portion A and the cuti `ting end portion B of the drill are formed of different material, as already stated, the former being preferably of an ordinarily comparatively low carbon Vsteel and the latter of alloy steel, such as tungsten-steel, especially adapted for high-speed cutting, as de scribed. These parts I first form separately into ungrooved cylindrical bars, as indicated in I'FigaA 4, 5, 8, and 9, the part A, with a reduced and preferablytapered screw-threaded extension 1, having an annular recess or groove 2 at the base thereof to form acylinfdrical ange or collar 3, and the part B a correspondinglyscrewthreaded recess or socket 4 and a reduced {iylindrical collar 5, adapted to accurately fit ind? said annular recess or groove 2 of the part A. This Work may be readily done at small cost by means of automatic machinery and suitable tools, insuring accuracy and interchangeability, so that `the two parts` will be closely fitted and seated, as required,

when screwed together for the grooving operation, Which is then effected as usual.

The parallel spiral grooves 6 6 thus cut in the united paits out away the walls of the recess or spcket 4 in the part B, so as to form side openings thereto, as indicated in Fig. 3, and also'cut into the extension 1 of the latter to less than the size of the side openings in part B, thus allowing the two symmetricallygrooved parts to be disengaged, as indicated in Fig. 10, by merelygiving approximately a quarter-turn to one part relative to the other, and theymay of course be reunited at any time in a similar manner by merely placing them in the Fig. 10 position, with their axes in line engaging the edges of the threads and giving aquarter-turn, which simultaneously sots the spiral grooves accurately into line with each other and firmly-seats the abutting ends, with the remaining segmental 'collar portions 3 of part A firmly inclosing the reduced segmental collar portions 5 ot' part B, so as to reinforce and thereby prevent possible spread of the latter.

Inorder tol .positively limit l the turning and 5. Fig. l() shows the two parts in posiu movement of one part upon the other, an

vIDC) thereby prevent possible slight misalinement of the grooves or undue jamming of the parts under strain of heavy surface, I insert a stoppin 10 at a proper point in the annular recess 2 of part A to engage a shoulder 1l, formed by cutting away a small end 'portion of the segmental collar on part B, thereby insuring the retention of the parts in symmetrical union, as indicated in Fig. 1, and I also provide against possible loosening of the connection between theparts during the withdrawal movement of the drill,by employing a setscrew 1Q, engaging a small lateral opening in the part B and adapted to be set up against the inserted extension 1 of part A.

The cutting end portions B, required for the renewal of old drills, are separately made in a lsimilar manner in connection with a standard body portion and their union made with the old body portion as preferably made in the department commonly provided to care for such tools.

lVhile, my complete invention is preferably employed in the manner particularlydescribed and shown, it is obvious that certain features thereof may he dispensed withor modified.

In the modification indicated in Fig. 11 the extension 1 upon the part A is socketed in the part B without employing the screwthreaded engagement of Figs. 1 to 10, the

engagement of the collar-segments, however, being similar to the preferred construction, and inclined ribs 1" being provided on one of the parts to engage a correspond ingly-grooved recess in the. other, and thereby prevent any turning of one part relative to the other.

'hat I claim ism I 1. A twist-drill, having a cutting end portion and a body portion, one of said portions having a threaded tapered extension and the other having a (-.m'responding axial recess to receive the same, said extension having its sides cut away to jointly form parts of the spiral grooves of the drill.

2. A twist-drill having a cutting end portion separably secured to a body portion by means of -an extension on one of said portions having a screw-threaded engagement with an axial recess therefor in the other portion, the sides of said extension and of said recessed portion being eut away to jointly form part I of the spiral grooves of the drill.

3. A twist-drill having a cutting end portion separably secured to a body portion by means of an extension on one of said portions havingga screw-threaded engagement with an axial recess therefor in the other portion, the sides of said extension and of said recessed portion being eut away to jointly form, part of the spiral grooves of the drill and the end of said extension being solidly bottomed in said recess.

4. A twist-drill, having a `cutting end pori means of an extension on one of said portions engaging an axial recess therefor in the other portion, the sides of said extension being eut away to form part of the spiral grooves of the drill and astop-pin and shoulder being provided on the abutting portions.

In testimony whereof 1 afix my signature in the presence of two witnesses.

WILLIAM `Rf DOWN. Witnesses:

1). M. STEWART, W. (i. STEWART. 

